import time

time1 = time.time()
a = ''
for i in range(10000000):
    a += 'sxt'

time2 = time.time()
print(time2 - time1)

time3 = time.time()
li = []
for i in range(10000000):
    li.append('sxt')
''.join(li)
time4 = time.time()
print(time4 - time3)
